This chapter provides an overview of training effectiveness evaluation so that the subsequent discussions of research will be more meaningful to the reader. There are three general issues in the basic methods of evaluation. The first issue concerns when the training effectiveness is measured. The second concerns how the training effectiveness is measured. The third issue concerns the validity of the measures that are used. Norm-referenced measures simply evaluate the trainees' standing compared to their peers, a naive group, or possibly a group of experts. The best information for evaluation of training can be acquired by using objective, criterion-referenced measures. In order to reliably measure performance effects, great care should be given to choosing the dependent variable in training effectiveness evaluation experiments. Most effectiveness evaluations require the presence of observersordata collectors to record the performance of trainees during training and transfer.